Embodiments of the present invention relate to a semiconductor device and a method for forming a silicon oxide film of a semiconductor device, and more particularly to a method for forming a semiconductor device by performing surface processing on a substrate using an amine-based compound to improve uniformity and density of a silicon oxide film provided over the semiconductor substrate.
In recent times, as information media, such as computers, has come into widespread use, technology for manufacturing semiconductor devices has rapidly developed. In a functional aspect, it is necessary for semiconductor devices to operate at a high speed and have a high storage capacity. Therefore, technology for manufacturing semiconductor devices has focused on improving integration, reliability, response time, etc.
In a conventional semiconductor device, a first metal line is formed over a semiconductor substrate, and an insulation film is formed to fill gaps between first metal lines. A via hole connected to the first metal line is formed in the insulation film, and a second metal line connected to the via hole is formed over the insulation film. The above-mentioned processes are repeated several times in the manufacturing of the semiconductor device. A borophosphosilicate glass (BPSG) with a superior gap-filling capability or a spin on dielectric (SOD) is deposited over the entire surface of the semiconductor substrate including the first metal line. The BPSG or SOD film is then annealed to form an insulation film.
However, since the semiconductor device includes μm-sized trenches, metal lines, via holes, etc., and is manufactured according to the Moore's Law, it becomes more difficult to form an even insulation film. In particular, when the BPSG or SOD film is formed at a temperature of 700° C. or less to reduce short channel effects, the BPSG film may be unevenly formed, and the SOD film may further affect package reliability.
In order to reduce the above-mentioned effects, silicon oxide film precursors have recently been proposed as an insulation material having improved gap-filling capabilities. For example, the silicon oxide film precursors may comprise i) polysilazane, which serves as an amine-based oxide precursor, and ii) trisilylamine (TSA), which serves as a flowable oxide (FO) precursor.
When the polysilazane is used as a silicon oxide film precursor, a polysilazane precursor is coated over a substrate. The coated substrate is then annealed at a temperature of 100-500° C., so that a silicon oxide film is formed, as indicated by the following reaction 1.

When the TSA is used as a silicon oxide film precursor, a TSA precursor is deposited over the substrate at a high temperature. After the deposition, hydrolysis between the TSA precursor and distilled water (H2O) occurs so that a silicon oxide film is formed, as indicated by the following reaction 2.N(SiH3)3(aq)+OH−+H+→3Si(OH)2(s)+2NH3(g)N(SiH3)3+9H2O→SiO2+NH3+12H2  [reaction 2]
However, as the size of a semiconductor device is reduced to 30 nm or less, when polysilazane precursor is used, it becomes more difficult to fill the gaps uniformly, and a void is formed in the silicon oxide film. In addition, bubbles (H2, NH3, N2, H2O) may be generated in the annealing process, such that the surface of the silicon oxide film becomes uneven, or a crack or the like occurs in the silicon oxide film.
If a TSA precursor is used, elements N and H contained in the TSA precursor have low heat transfer rates. Accordingly, when a TSA film having a thickness of 1-10K Å is used to fill in a high-aspect-ratio trench or between metal lines, the generated NH3 gas may not be sufficiently volatilized, or the Si—N bond may not be decomposed, even though the annealing process is performed at a high temperature of 100° C. or higher. As a result, a SiO2 conversion rate is low, and a lower portion of a film does not change to an oxide film. Thus, defects, such as cracks, micro-pores, distribution, or delamination, etc. are generated in the silicon oxide film. Moreover, since a contact interface may be polluted by N and H outgassing, Rc resistance of a metal line or a via hole may be deteriorated. The unsubstituted NH groups accumulated at a sidewall of a gate further result in the formation of cracks.
In accordance with the above-mentioned conventional method, substitution of the silicon oxide precursor into the silicon oxide film (13) may not be complete, even though annealing is performed at a high temperature. Accordingly, the unsubstituted nitrogen (N) particles (i.e., white particles (15) shown in the Electron Energy Loss Spectrometer (EELS) analysis result of FIG. 1) are present between high-aspect-ratio gate patterns (11), and defects, such as cracks, micro-pores, delamination, etc., occur in the silicon oxide film.
There are a variety of factors that affect the substitution of the silicon oxide precursor. For example, factors may include distilled water processing, ozone (O3) processing, heat processing, etc. Thus, there is a need to improve the conversion rate from the silicon oxide precursor to the silicon oxide film, and to develop a method for optimizing distilled-water processing and thermal processing (or annealing).